Supervisory method and system for improved control model updates applied to dynamic balancing

ABSTRACT

A method for dynamically balancing a rotating system through strategic control model updates, wherein said system contains sensors and sensor measurements whose responses to control actions are used to represent the system through a control model, where said control model and sensor measurements are used to determine future control actions is disclosed. The performance of the control model is evaluated using sensor measurements and responses; the evaluation is further used to determine if it is necessary to update the control model. The ongoing performance of the current control model is anticipated utilizing rate-of-change metrics obtained by evaluating said sensor measurements and responses. When a new control model is needed, further evaluation is done to determine if sensor measurements and responses are adequate for updating the control model. When control model performance is poor and past control actions not adequate to update the control model or when system-operating conditions have changed substantially and control performance is questionable, select control actions are computed. These control actions excite the rotating system to provide sufficiently different sensor measurement response adequate to update the control model. In both cases, the select control action minimizes the negative effects on the balance system. The performance evaluations and select control actions are incorporated into a balance control procedure, thereby improving balance times and facilitating achievement of maximum spin speeds in a self-balancing system.

RELATED APPLICATIONS

[0001] This application is related to co-pending and co-owned patentapplications entitled: “Method and Apparatus for Reducing MicroprocessorSpeed Requirements in Data Acquisition Applications,” Honeywell DocketNo. M10-01121, U.S. Ser. No. 09/792,996, filed on Feb. 26, 2001; “Methodand System for Detecting Fluid Injection from Stationary to RotatingMembers,” Honeywell Docket No. M10-01128, U.S. Ser. No. ______, filed onFeb. 26, 2001; “Simultaneous Injection Method and System for aSelf-Balancing Rotatable Apparatus,” Honeywell Docket H16-26312, U.S.Ser. No. 09/896,763, filed on Jun. 29, 2001; “Energy-Based ThresholdsApplied to Dynamic Balancing,” Honeywell Docket No. H16-02079, U.S. Ser.No. ______, filed on Sep. 10, 2001; Honeywell Docket No. H16-26311, U.S.Ser. No. ______, filed on Sep. 10, 2001; “Continuous Flow Method andSystem for Placement of Balancing Fluid on a Rotating Device RequiringDynamic Balancing”, Honeywell Docket H16-01112, U.S. Ser. No. ______,filed on Nov. 15, 2001; “Dynamic Balancing Application Mass Placement”,Honeywell Docket H16-01117, U.S. Ser. No. ______, filed on Nov. 15,2001; “Fixed-Bandwidth Correlation Window Method and System for aSelf-Balancing Rotatable Apparatus,” Honeywell Docket No. M10 02075,U.S. Ser. No. ______, filed on Nov. 15, 2001; “Data Manipulation Methodand System for a Self-Balancing Rotatable Apparatus,” Honeywell DocketNo. H16-02078, U.S. Ser. No. ______, filed on Nov. 15, 2001; “ResonanceIdentification Extension for a Self-Balancing Rotatable Apparatus,”Honeywell Docket No. H16-02080, U.S. Ser. No. 09/792,996, filed on Nov.15, 2001; “Method and System for Mechanizing Simultaneous Multi-ActuatorActions Applied to Dynamic Balancing,” Honeywell Docket No. H16-26313,U.S. Ser. No. ______, filed on Nov. 15, 2001.

TECHNICAL FIELD

[0002] The present invention relates generally to rotatable members thatare able to achieve balanced conditions throughout a range of rotationalspeeds. The present invention also relates to methods and systems fordynamically balancing rotatable members through the continualdetermination of out of balance forces and motion to thereby takecorresponding counter balancing action. The present inventionadditionally relates to methods and system for improving control modelupdates applied to dynamic balancing.

BACKGROUND OF THE INVENTION

[0003] Mass unbalance in rotating machinery leads to machine vibrationsthat are synchronous with the rotational speed. These vibrations canlead to excessive wear and to unacceptable levels of noise. Typicalimbalances in large, rotating machines are on the order of oneinch-pound.

[0004] It is a common practice to balance a rotatable body by adjustinga distribution of moveable, inertial masses attached to the body. Thisstate of balance may remain until there is a disturbance to the system.A tire, for instance, can be balanced once by applying weights to it.This balanced condition will remain until the tire hits a very big bumpor the weights are removed. However, certain types of bodies that havebeen balanced in this manner will generally remain in balance only for alimited range of rotational velocities. A centrifuge for fluidextraction, however, can change the amount of balance as more fluid isextracted.

[0005] Many machines are also configured as freestanding spring masssystems in which different components thereof pass through resonanceranges, during which the machine may become out of balance.Additionally, such machines may include a rotating body loosely coupledto the end of a flexible shaft rather than fixed to the shaft as in thecase of a tire. Thus, moments about a bearing shaft may also be createdmerely by the weight of the shaft. A flexible shaft rotating at speedsabove half of its first critical speed can generally assume significantdeformations, which add to the imbalance. This often poses problems inthe operation of large turbines and turbo generators.

[0006] Machines of this kind usually operate above their first criticalspeed. As a consequence, machines that are initially balanced atrelatively low speeds may tend to vibrate excessively as they approachfull operating speed. Additionally, if one balances to an acceptablelevel rather than to a perfect condition (which is difficult tomeasure), the small remaining “out-of-balance” will progressively applygreater force as the speed increases. This increase in force is due tothe fact that F is proportional to rω² (note that F is the out ofbalance force, r is the radius of the rotating body and ω is itsrotational speed).

[0007] The mass unbalance distributed along the length of a rotatingbody gives rise to a rotating force vector at each of the bearings thatsupport the body. In general, the force vectors at respective bearingsare not in phase. At each bearing, the rotating force vector may beopposed by a rotating reaction force, which can be transmitted to thebearing supports as noise and vibration. The purpose of active, dynamicbalancing is to shift an inertial mass to the appropriate radialeccentricity and angular position for canceling the net unbalance. Atthe appropriate radial and angular distribution, the inertial mass cangenerate a rotating centrifugal force vector equal in magnitude andphase to the reaction force referred to above.

[0008] Many different types of balancing schemes are known to thoseskilled in the art. When rotatable objects are not in perfect balance,nonsymmetrical mass distribution creates out-of-balance forces becauseof the centrifugal forces that result from rotation of the object.Although rotatable objects find use in many different applications, oneparticular application is a rotating drum of a washing machine.

[0009] U.S. Pat. No. 5,561,993, which was issued to Elgersma et al. onOct. 22, 1996, and is incorporated herein by reference, discloses aself-balancing rotatable apparatus. Elgersma et al. disclosed a methodand system for measuring forces and motion via accelerations at variouslocations in a system. The forces and moments were balanced through theuse of a matrix manipulation technique for determining appropriatecounterbalance forces located at two axial positions of the rotatablemember. The method and system described in Elgersma et al. accounted forpossible accelerations of a machine, such as a washing machine, whichcould not otherwise be accomplished if the motion of the machine werenot measured. Such a method and system was operable in association withmachines not rigidly attached to immovable objects, such as concretefloors. The algorithm disclosed by Elgersma et al. permittedcounterbalance forces to be calculated even when a washing machine islocated on a flexible or mobile floor structure combined with carpet andpadding between the washing machine and a rigid support structure.

[0010] U.S. Pat. No. 5,561,993 thus described a dynamic balance controlalgorithm for balancing a centrifuge for fluid extraction. To accomplishsuch balance control, sensor responses to balancing control actions on acentrifuge may be modeled and utilized to determine control actions todrive an associated system toward a balanced state. Such a system isgenerally time variant, such that the control models utilized thereincan be routinely updated based on the measured response to a previouscontrol action, which is a variation of perturbation theory, well knownin the art. The control algorithm explained in U.S. Pat. No. 5,561,993simply updated the control models after every designated control action.The present inventors realize, however, that such a control method canlead to unneeded model updates or the creation of poor models resultingin inadequate predictions. This in turn can lead to lengthy balancingtimes and the inability to obtain maximum spin speeds in centrifugeenvironments, such as, for example, a clothes washing machine.

[0011] The present inventors have thus concluded that previous methodsfor dynamically balancing a rotatable member have experienced severelimitations in the degree of balance that can be achieved and in therotational speeds under which they operate. The present inventorsconclude that it would be desirable to recognize when existing controlmodels for balancing loads are no longer performing well. The presentinventors also believe that it would be desirable to recognize when theresults of a previous control action are adequate to support a controlmodel update, and thereby provide a basis for updating the control modelin a timely fashion to ensure that the control model sufficientlyrepresents the system requiring balancing. The present inventors haveadditionally concluded that it would be desirable to implement methodsand systems for computing new test actions that are based on informationobtained from the system rather than applying random perturbations tothe system at each new speed or when it is confirmed that the controlaction is not having the desired affect. The invention disclosed hereinthus addresses these needs.

BRIEF SUMMARY OF THE INVENTION

[0012] The following summary of the invention is provided to facilitatean understanding of some of the innovative features unique to thepresent invention and is not intended to be a full description. A fullappreciation of the various aspects of the invention can be gained bytaking the entire specification, claims, drawings, and abstract as awhole.

[0013] It is one aspect of the present invention to provide methods andsystems in which rotatable members can achieve balanced conditionsthroughout a range of rotational speeds.

[0014] It is another aspect of the present invention to provide methodsand systems for dynamically balancing rotatable members through thecontinual determination of out-of-balance forces and motion to therebytake corresponding counter balancing action.

[0015] It is still another aspect of the present invention to providemethods and systems for improving control model updates applied todynamic balancing.

[0016] In accordance with various aspects of the present invention,methods and systems are disclosed herein for dynamically updating acontrol model for controlling a balance state of a rotating device orrotating system. Sensor responses can be utilized to define a controlmodel that, along with sensor measurements, can be used to determinecontrol actions that drive the rotatable apparatus to a balanced stateand provide new sensor responses. Recognizing when an existing controlmodel is no longer performing well, and when the results of a previouscontrol action are adequate to support a control model update, a basisis provided for updating the control model in a timely fashion andensuring that it sufficiently represents the rotatable apparatus. Aglobal or aggregate metric, along with a sensor distribution metric, maybe calculated from sensor measurements and evaluated to determine if itis necessary to update the control model and to determine if the recentsensor response is sufficient to update the control model. Theperformance of the control model may be evaluated utilizing rate ofchange data obtained by evaluating sensor measurements from one controlaction to the next. When prior control actions are not adequate forcontrol model update, or the system experiences a significantoperational change, forced control actions (test actions) may becomputed with the intent of moving along the anticipated bestbalance-control trajectory and doing this with two sufficientlydifferent control actions so as to provide sufficient system responsefor a control model update. The collection of these methods and systemsensure timely control model updates for an accurate control model underchanging system conditions, thereby improving balance times andenhancing the achievement of maximum spin speeds in a rotating system.Similar techniques may be utilized to determine whether or not abalanced state (i.e., threshold) has been met or exceeded.

[0017] The present invention thus makes possible an improved dynamicbalancing procedure that accounts for both forces and motion that may beimposed on a rotating member or rotating apparatus, such as the drum ofa washing machine.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying figures, in which like reference numerals referto identical or functionally-similar elements throughout the separateviews and which are incorporated in and form part of the specification,further illustrate the present invention and, together with the detaileddescription of the invention, serve to explain the principles of thepresent invention.

[0019]FIG. 1 depicts a plot of a non-linear system, in accordance withpreferred embodiments of the present invention;

[0020]FIG. 2 illustrates a graphical representation of a nonlinearsystem and the effect of system noise with which the present inventionis concerned;

[0021]FIG. 3 depicts a schematic representation of a washing machine,which may be adapted for use in association with the present invention;

[0022]FIG. 4 illustrates a spring and mass illustration depicting themanner in which a nonrigid washing machine can behave if mounted onnonrigid structures;

[0023]FIG. 5 depicts a three-dimensional schematic representation of theforces and critical lengths along an axis of rotation, which has beenextended along a length of the shaft and through a length of the drum;

[0024]FIGS. 6 and 7 depict a graphical representation of a shaft withmeasured forces and accelerations;

[0025]FIG. 8 depicts a state-transition-type diagram illustratingoperational steps for mass placement, in accordance with preferredembodiments of the present invention;

[0026]FIG. 9 illustrates a state-transition-type diagram illustratingoperational steps for implementing a balance loop, in accordance withpreferred embodiments of the present invention;

[0027]FIG. 10 depicts a state-transition-type diagram illustratingoperational steps for computing test actions, in accordance withpreferred embodiments of the present invention;

[0028]FIG. 11 illustrates a state-transition-type diagram depictingoperational steps that may be implemented to determine if controlactions are sufficiently different from one another, in accordance withpreferred embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0029] The particular values and configurations discussed in thesenon-limiting examples can be varied and are cited merely to illustratean embodiment of the present invention and are not intended to limit thescope of the invention.

[0030] The present invention is generally an improvement to theinvention disclosed in U.S. Pat. No. 5,561,993. The basic configurationand concepts explained in U.S. Pat. No. 5,561,993 are disclosed hereinbut in no way limit the scope of the invention described and claimedherein. Features revealed in U.S. Pat. No. 5,561,993 are presentedherein for illustrative purposes only in order to explain the foundationfrom which the present invention has been derived. Those skilled in theart can appreciate that such features, including figure, text,descriptions, equations and tables thereof, do not limit the scope ofthe present invention.

[0031]FIG. 1 depicts a plot of a non-linear system 1, in accordance withpreferred embodiments of the present invention. Given a very simple(e.g., one-dimensional) non-linear system, such as the non-linear systemin FIG. 1, the system can be balanced when the sensor measurement, f(m),is driven to zero. The objective of such a system is to find a value fora counterbalance Am, such that the sensor measurement f(m) is driven tozero, i.e., f(m)=0. Utilizing a Taylor's series expansion in thevicinity of the anticipated operating range and neglecting second orderand higher terms, results in a linear model of the form y=b+mx. Thelinear model can be written to reflect the example illustrated in FIG.1, where several possible line estimates are shown; equation 1 expressesthis relationship. $\begin{matrix}{{f\left( m_{next} \right)} \approx {{f\left( m_{aftertest} \right)} + {\left( \frac{\partial{f(m)}}{\partial m} \right) \cdot \left( {m_{next} - m_{aftertest}} \right)}}} & (1)\end{matrix}$

[0032] Those skilled in the art can appreciate that f(m_(next))represents the desired sensor measurement. In addition, f(m_(aftertest))can represent the sensor measurement after a test action or a priorbalance-control action. The variable m generally represents the out ofbalance in the system. For example, the variable m_(aftertest) generallyrepresents the out-of-balance after a test action (Δm_(test)), and thechange in m, (i.e. Δm=m_(next)−m_(aftertest)), is the counterbalancerequired to achieve a desired sensor measurement, (f(m_(next)=)0). Thecontrol action involves moving in the direction of the estimatedcounterbalance and updating the system model and the requiredcounterbalance estimate as control progresses. Those skilled in the artcan appreciate that this control implementation of equation 1 representsthe well-known Newton Raphson iteration method.

[0033] Since the objective is to find f(m_(next))=0, the general form ofthe equation reduces to: $\begin{matrix}{m_{next} = {m_{aftertest} - {\left\lbrack \frac{\partial{f(m)}}{\partial m} \right\rbrack^{- 1} \cdot {f\left( m_{aftertest} \right)}}}} & (2)\end{matrix}$

[0034] where m_(next) is the solution or system out of balance needed tomake f(m_(next))=0 or

[0035] to drive the sensor measurement to zero. Thus, the estimated masschange Δm_(cb) generally required for counterbalance action isillustrated in equation 3. $\begin{matrix}{{\Delta \quad m_{cb}} = {{m_{next} - m_{aftertest}} = {{- {f\left( m_{aftertest} \right)}}/\left( {\frac{\partial f}{dm}\left( m_{aftertest} \right)} \right)}}} & (3)\end{matrix}$

[0036] The partial derivative, or slope of the sensor function, can befound by perturbing the system. This may be generally illustrated inequation 4, which represents the change in sensor measurements due to atest action (Δm_(test)=m_(aftertest)−m_(beforetest)). $\begin{matrix}{{\frac{\partial f}{dm}\left( m_{aftertest} \right)} = \frac{{f\left( m_{aftertest} \right)} - {f\left( m_{beforetest} \right)}}{m_{aftertest} - m_{beforetest}}} & (4)\end{matrix}$

[0037] Combining equations 3 and 4 may result in the generalized formshown in equation 5, which equation is generally expressed as anexpanded notion of multiple inputs and outputs. $\begin{matrix}{\left\lbrack {f\left( m_{aftertest} \right)} \right\rbrack = {{- \left\lbrack \frac{\partial{f(m)}}{\partial m} \right\rbrack} \cdot \left\lbrack {\Delta \quad m_{solution}} \right\rbrack}} & (5)\end{matrix}$

[0038] Regarding the linear models and associated slope calculation inFIG. 1, it can be appreciated that a change in the mass may result in achange in the system, and the system itself may be nonlinear; thus, thelinear model used to determine the next counterbalance may havesignificant error. Therefore, when applying the Newton Raphson iterationto a process, certain requirements should be followed. First, theinitial approximation should be sufficiently accurate to result insubsequent operation near the desired solution and the measurement'sf(m) being smooth, nearly linear and single-valued in the vicinity ofthe anticipated operation. Additionally, because higher derivatives areneglected in this type of approximation, the higher derivatives shouldbe small, so as to avoid convergence problems.

[0039] Lastly, in applications of the Newton Raphson iteration, only onesolution of mass Δm_(cb) should exist for the sensor measurement beingequal to zero. This means there is only one root. Even after followingthe above requirements, system noise may be a concern. In thehypothetical illustration of FIG. 2, a larger initial test action, whichchanges the system to point C, is preferable to the one that changes itto point B. Comparing the slopes of lines 22, 24 and 26, which resultfrom the various test mass perturbations depicted in FIG. 2, canevidence system noise issues. The difference between the before andafter test measurement should be large enough to obtain a goodapproximation of the slope of the function and ensure the resultingchange in the measurement dominates the changes due to system noise.

[0040]FIG. 3 depicts a schematic representation of a washing machine,which may be adapted for use in association with the present invention.Those skilled in the art can appreciate that the present invention maybe implemented within a rotating device or rotating system, such as, forexample, a washing machine. Those skilled in the art can furtherappreciate, however, that other types of rotatable systems or rotatingdevices may be utilized in accordance with the present invention. Notethat as utilized herein, the terms “rotating system,” “rotating device,”“rotating apparatus,” “rotatable apparatus,” “rotatable system,” or“rotatable device” may be utilized interchangeably. The methods andsystems of the present invention may be implemented to balance rotatingsystems, rotating devices or rotating members thereof. Such rotatingsystems or rotating devices may be configured as, for example, washingappliances. Examples of such washing appliances may include washingmachines, dishwashers, circuit board cleaners, and so forth.

[0041] In the example of FIG. 3 the basic mechanism of dynamic balancinginvolves counter balancing the out-of-balance load by injecting waterinto a plurality of cups placed at front and back axial planes,identified by reference numbers 80 and 82 in FIG. 3, of the rotatabledrum. Although the terms “test mass” or “mass” may be utilizedinterchangeably in the context of one or more embodiments of the presentinvention to refer to a “fluid mass,” those skilled in the art canappreciate that such a test mass or mass may be comprised of manydifferent materials, and the invention is not limited to fluid-basedinjection for placing mass.

[0042]FIG. 3 thus schematically illustrates a washing machine comprisinga frame 50, a shaft 52 and a rotatable drum 54. Shaft 52 may be attachedto rotatable drum 54. These two components can be attached to a rotor orpulley 56 of a motor drive. Frame 50 can provide support for a bearinghousing 58 in which bearings, 60 and 62, are generally supported. Ahousing mount 64 can support bearing housing 58. A plurality of sensorsidentified by the reference numeral 70 is illustrated at locationsbetween the housing mount and the bearing housing in FIG. 3. Thesesensors will be described in greater detail below. Beneath frame 50 aregenerally shown a carpet and pad 74, a plywood support member 76 and aplurality of joists 78. The representation shown in FIG. 3 illustrates atypical application of a horizontal washing machine in a residentialhousing environment. Those skilled in the art can appreciate that FIG. 3is presented for illustrative purposes only and that a variety ofwashing machine configurations and other rotating devices notillustrated herein may be utilized to implement varying embodiments ofthe present invention.

[0043] With continued reference to FIG. 3, the rotatable drum 54 may beshown having a plurality of schematically illustrated back cups 80 andfront cups 82. Both the front and back cups may be disposed at axialends of the rotatable drum 54 and, although not shown in FIG. 3, boththe front and back cups can comprise a plurality of cups dispersedaround the periphery of the drum. A quantity of water can be injectedinto the cups from a stationary control valve supplied with water, suchas those identified by reference numerals 90 and 92.

[0044] Some balancing systems assume that the machine may be attachedrigidly to an immovable object or footing, such as a concrete floor. Inmost practical residential housing applications, however, the machine isnot rigidly attached to an immovable object and, instead, may beassociated with a plurality of flexible members. For example, FIG. 4,depicts a schematic representation of a type of arrangement usuallyencountered in washing machine applications. FIG. 4 thus illustrates aspring and mass diagram depicting the manner in which a nonrigid washingmachine can behave if mounted on nonrigid structures.

[0045] The behavior of frame 50 in relation to footing 79 can bedescribed as a spring representing frame 50 and floor 76 and having aspring constant K1. The relationship between a tub 53 surrounding therotatable drum 54 and frame 50 can be described by a spring constant K2.A spring constant K3 represents the relationship between bearing housing58 and housing mount 64, and frame 50 in FIG. 3. Lastly, FIG. 4illustrates a spring constant K4 that represents the bending of shaft 52along with rotatable members 54 and 56.

[0046] Although only represented by boxes in FIG. 4, the schematicillustration depicts a multitude of mass-spring subsystems that definethe relationships among major components of the overall system. Onepurpose for illustrating FIG. 4 is to demonstrate that the relationshipsamong these components are not rigid and, as a result, can permitmotion, resulting in accelerations, to occur in response to forcesexerted on the various components. Therefore, if the system is not rigidand only forces are measured by the sensors 70 shown in FIG. 3, accuratecounterbalance determinations would be extremely difficult, if notimpossible, to make.

[0047]FIG. 5 illustrates a three-dimensional schematic representation ofthe forces and critical lengths along the axis of rotation, which hasbeen extended along the length of the shaft and through the length ofthe drum. Force sensors may be mounted to measure the force transmittedbetween housing mount 64 and bearing housing 58, as illustrated in FIG.2. The basic concept of dynamic balancing stipulates that vector forcesat the front and back cups may represent an out-of-balance condition.Referring to FIG. 5, the system may be provided with a mechanism forsensing a first force F_(backsensor) at a first location 100 of the axisof rotation and a second mechanism for measuring a second forceF_(frontsensor) at a second location 102 of the axis of rotation. Itshould be understood that both the first and second forces shown in FIG.5 are likely to be determined from a plurality of force sensors arrangedso that the resultant force vectors along multiple axes of the system,can be determined at each of the first and second locations, 100 and102, of the axis of rotation.

[0048] If a washing machine or similar apparatus with a rotating memberis rigidly attached to an unmovable object, such as a concrete floor, insuch a way that movement of the machine is prevented, a mere force andmoment analysis based on forces and moment arms shown in FIG. 5 would beappropriate and, thus, yield sufficient information to allowcounterbalance forces to be implemented in a manner that would achieve abalance of a rotating drum 54. As discussed above in association withFIGS. 3 and 4, however, it is not practical to expect a machine of thistype to be installed and operate without motion being experienced by thevarious portions of the machine. Therefore, it may be beneficial tomeasure motion relative to a footing or inertial space (e.g.,acceleration) and account for it in the analysis of forces.

[0049]FIGS. 6 and 7 show the measurement of forces and accelerations inthree-dimensional space at various locations along the shaft 52. ViewingFIGS. 6 and 7 together, it can be seen that the forces and accelerationscan be measured at two coincident locations on the shaft 52. It can beappreciated, however, that this coincidence of the first force and thefirst acceleration or the second force and the second acceleration arenot requirements of the present invention. At each of the first andsecond locations, 100 and 102, the effects of rotating out-of-balanceforces are determined along the horizontal (h) and vertical (v)coordinates. It can be appreciated by those skilled in the art that thecoordinates illustrated in FIGS. 6 and 7 represent the fact that theconcepts in U.S. Pat. No. 5,561,993 and the present invention operatewith information describing the forces in terms of a magnitude, a fixeddirection and an associated rotating drum angle. Similarly, the motion(e.g., accelerations) may also be expressed as a magnitude along a fixeddirection with an associated rotating drum angle. TABLE 1 VARIABLEMEANING Inputs Δm_(front)_cb test counterbalance mass placed in thefront plane (vector) Δm_(back)_cb test counterbalance mass placed in theback plane (vector) ωback speed of rotation in (rad/sec) at which theback plane test counterbalance occurred ωfront speed of rotation in(rad/sec) at which the front plane test counterbalance occurred R radiusof counterbalance placement (inches) ω current speed of rotation Outputsf_(back) back force sensor (Ibf) (vector) f_(front) front force sensor(Ibf) (vector) a_(back) back accelerometer sensor (in/sec²) (vector)a_(front) front accelerometer sensor (in/sec²) (vector) Actionsm_(backplane)_cb estimated backplane counterbalance to drive sensorreadings to zero (vector) m_(frontplane)_cb estimated frontplanecounterbalance to drive sensor readings to zero (vector)

[0050] For the following discussion, Table I illustrates the inputs andoutputs utilized in the multi-input/multi-output condition relating tothe invention described in U.S. Pat. No. 5,561,993. In order to find theappropriate solutions for the counterbalance forces described above,measured forces and accelerations should be considered in the balancingof system forces and moments. As described above, the counterbalancemasses, forces and accelerations represent magnitudes and angles.Therefore, all variables shown in Table I, except r and w, generallycomprise both a magnitude and an angle in polar coordinates, which canbe converted to complex coordinates. The relationship described inequation 5 above can be rewritten for the multi-input/multi-output caseto result in four coupled simultaneous equations, incorporating theeffects of perturbations in both front and back planes that could haveoccurred at rotational speeds slightly different from the current speed.These four relationships are shown below and are identified as equation6. $\begin{matrix}\begin{matrix}{a_{back4} = {{{- \left( \frac{a_{back1} - a_{back0}}{{{r \cdot \omega_{back}^{2} \cdot \Delta}\quad m_{back\_ cb}}~} \right)} \cdot r \cdot \omega^{2} \cdot m_{backplane\_ cb}} - {\left( \frac{a_{back3} - a_{back2}}{{r \cdot \omega_{front}^{2} \cdot \Delta}\quad m_{front\_ cb}} \right) \cdot r \cdot \omega^{2} \cdot m_{frontplane\_ cb}}}} \\{a_{front4} = {{{- \left( \frac{a_{front1} - a_{front0}}{{r \cdot \omega_{back}^{2} \cdot \Delta}\quad m_{back\_ cb}} \right)} \cdot r \cdot \omega^{2} \cdot m_{backplane\_ cb}} - {\left( \frac{a_{front3} - a_{front2}}{{r \cdot \omega_{front}^{2} \cdot \Delta}\quad m_{front\_ cb}} \right) \cdot r \cdot \omega^{2} \cdot m_{frontplane\_ cb}}}} \\{{f_{back4} = {{{- \left( \frac{f_{back1} - f_{back0}}{{r \cdot \omega_{back}^{2} \cdot \Delta}\quad m_{back\_ cb}} \right)} \cdot r \cdot \omega^{2} \cdot m_{backplane\_ cb}} - {\left( \frac{f_{back3} - f_{back2}}{{r \cdot \omega_{front}^{2} \cdot \Delta}\quad m_{front\_ cb}} \right) \cdot r \cdot \omega^{2} \cdot m_{frontplane\_ cb}}}}~} \\{f_{front4} = {{{- \left( \frac{f_{front1} - f_{front0}}{{{r \cdot \omega_{back}^{2} \cdot \Delta}\quad m_{back\_ cb}}~} \right)} \cdot r \cdot \omega^{2} \cdot m_{backplane\_ cb}} - {\left( \frac{f_{front3} - f_{front2}}{{r \cdot \omega_{front}^{2} \cdot \Delta}\quad m_{front\_ cb}} \right) \cdot r \cdot \omega^{2} \cdot m_{frontplane\_ cb}}}}\end{matrix} & (6)\end{matrix}$

[0051] The four mathematical relationships illustrated in equation 6above can be grouped together as a single equation because they aretreated as a matrix in the following discussion. The meanings of thesubscripts in equation 6 above are identified in Table II. TABLE IISUBSCRIPT MEANING 0 Measurement prior to backplane counter-balance testmass Δm_(back)_cb 1 measurement after backplane counter_balance testmass Δm_(back)_cb 2 measurement prior to frontplane counterbalance testmass Δm_(front)_cb 3 measurement after frontplane counterbalance testmass Δm_(front)_cb 4 current sensor measurement

[0052] The relationships shown above in equation 6 can be applied toequation 5 in matrix form as: $\begin{matrix}{\begin{bmatrix}a_{{back}\quad 4} \\a_{{front}\quad 4} \\f_{back4} \\f_{front4}\end{bmatrix} = {{- \begin{bmatrix}\frac{a_{{back}\quad 1} - a_{{back}\quad 0}}{{r \cdot \omega_{back}^{2}}\Delta \quad m_{back\_ cb}} & \frac{a_{back3} - a_{back2}}{{r \cdot \omega_{front}^{2}}\Delta \quad m_{back\_ cb}} \\\frac{a_{front1} - a_{{front}\quad 0}}{{r \cdot \omega_{back}^{2}}\Delta \quad m_{back\_ cb}} & \frac{a_{{front}\quad 3} - a_{{front}\quad 2}}{{r \cdot \omega_{front}^{2}}\Delta \quad m_{front\_ cb}} \\\frac{f_{back1} - f_{back0}}{{r \cdot \omega_{back}^{2}}\Delta \quad m_{back\_ cb}} & \frac{f_{back3} - f_{back2}}{{r \cdot \omega_{front}^{2}}\Delta \quad m_{front\_ cb}} \\\frac{f_{{front}\quad 1} - f_{{front}\quad 0}}{{r \cdot \omega_{back}^{2}}\Delta \quad m_{back\_ cb}} & \frac{f_{{front}\quad 3} - f_{front2}}{{r \cdot \omega_{front}^{2}}\Delta \quad m_{front\_ cb}}\end{bmatrix}} \cdot \begin{bmatrix}m_{backplane\_ cb} \\m_{frontplane\_ cb}\end{bmatrix} \cdot r \cdot \omega^{2}}} & (7)\end{matrix}$

[0053] where we describe this matrix equation as being in the form b=Axand $\begin{matrix}{A = {{- \frac{\partial{f(m)}}{\partial m}} = {- \begin{bmatrix}\frac{a_{back1} - a_{back0}}{{r \cdot \omega_{back}^{2} \cdot \Delta}\quad m_{back\_ cb}} & \frac{a_{back3} - a_{back2}}{{r \cdot \omega_{front}^{2} \cdot \Delta}\quad m_{front\_ cb}} \\\frac{a_{front1} - a_{front0}}{{r \cdot \omega_{back}^{2} \cdot \Delta}\quad m_{back\_ cb}} & \frac{a_{{front}\quad 3} - a_{{front2}\quad}}{{r \cdot \omega_{front}^{2} \cdot \Delta}\quad m_{front\_ cb}} \\\frac{f_{back1} - f_{back0}}{{r \cdot \omega_{back}^{2} \cdot \Delta}\quad m_{back\_ cb}} & \frac{f_{back3} - f_{back2}}{{r \cdot \omega_{front}^{2} \cdot \Delta}\quad m_{front\_ cb}} \\\frac{f_{front1} - f_{front0}}{{r \cdot \omega_{back}^{2} \cdot \Delta}\quad m_{back\_ cb}} & \frac{f_{front3} - f_{front2}}{{{r \cdot \omega_{front}^{2} \cdot \Delta}\quad m_{front\_ cb}}~}\end{bmatrix}}}} & (8)\end{matrix}$

[0054] Equations 6, 7 and 8 depict the mathematical model generallydescribed in U.S. Pat. No. 5,561,993. This mathematical model isformulated such that the dynamics of the system are divided into twocolumns based on whether mass is placed in the front plane (i.e., column2) or the back plane (i.e., column 1) of the spinner. The presentinvention disclosed herein may be used with this control model or likeextensions, the more general solution of which allows for the placementof mass in both the front and the back plane simultaneously to formulatethe control model and apply control actions. This more general controlmodel solution is briefly discussed and used herein for describing thepresent invention.

[0055] For the more general control model solution, the model developedin equations 5, 6, and 7, take on the general form shown in equation 9.$\begin{matrix}{{f\left( {j + 2} \right)} = {- {{\left\lbrack {\frac{{f\left( {i + 1} \right)} - {f(i)}}{{{m\left( {i + 1} \right)} - {m(i)}}}\frac{{f\left( {i + 2} \right)} - {f\left( {i + 1} \right)}}{{{m\left( {i + 2} \right)} - {m\left( {i + 1} \right)}}}} \right\rbrack \left\lbrack {\frac{{m\left( {i + 1} \right)} - {m(i)}}{{{m\left( {i + 1} \right)} - {m(i)}}}\frac{{m\left( {i + 2} \right)} - {m\left( {i + 1} \right)}}{{{m\left( {i + 2} \right)} - {m\left( {i + 1} \right)}}}} \right\rbrack}^{- 1}\begin{bmatrix}{\Delta \quad m_{back}} \\{\Delta \quad m_{front}}\end{bmatrix}}}} & (9)\end{matrix}$

[0056] In equation 9 above, f(i) represents the i^(th) sensor reading;f(i+2) is equivalent to f(m_(aftertest)) illustrated in equation 5.Also, m(i) may be a complex vector representing the force at the frontand back planes of the rotating apparatus resulting from the i^(th) testaction. The equation Δm(i+1)=m(i+1)−m(i) may represent a complex vectorof counter balance force or test actions applied to the spinner; eachtest action is formed by injecting simultaneously in the front and theback plane of the spinner. The A matrix (df(m)/dm) obtained fromequation 5 is now represented by the relation shown in equation 10.$\begin{matrix}{A = {{- \frac{\partial f}{\partial{m(i)}}} = {- {\left\lbrack {\frac{{f\left( {i + 1} \right)} - {f(i)}}{{{m\left( {i + 1} \right)} - {m(i)}}}\frac{{f\left( {i + 2} \right)} - {f\left( {i + 1} \right)}}{{{m\left( {i + 2} \right)} - {m\left( {i + 1} \right)}}}} \right\rbrack \left\lbrack {\frac{{m\left( {i + 1} \right)} - {m(i)}}{{{m\left( {i + 1} \right)}{m(i)}}}\frac{{m\left( {i + 2} \right)} - {m\left( {i + 1} \right)}}{{{m\left( {i + 2} \right)} - {m\left( {i + 1} \right)}}}} \right\rbrack}^{- 1}}}} & (10)\end{matrix}$

[0057] Equation 11 below shows the A matrix for the more general controlmodel solution, where 2 control actuators, or control planes, and 4sensor readings are available as in the case of equations 6 through 8.$\begin{matrix}{A = {{- \begin{bmatrix}\frac{a_{back1} - a_{back0}}{{{\Delta \quad {m(1)}_{cb}}}} & \frac{a_{back2} - a_{back1}}{{{\Delta \quad {m(2)}_{cb}}}} \\\frac{a_{front1} - a_{front0}}{{{\Delta \quad {m(1)}_{cb}}}} & \frac{a_{front2} - a_{front1}}{{{\Delta \quad {m(2)}_{cb}}}} \\\frac{f_{back1} - f_{back0}}{{{\Delta \quad {m(1)}_{cb}}}} & \frac{f_{back2} - f_{back1}}{{{\Delta \quad {m(2)}_{cb}}}} \\\frac{a_{front1} - a_{front0}}{{{\Delta \quad {m(1)}_{cb}}}} & \frac{a_{front2} - a_{front1}}{{{\Delta \quad {m(2)}_{cb}}}}\end{bmatrix}} \cdot {\quad\begin{bmatrix}\frac{\Delta \quad {m(1)}_{back\_ cb}}{{{\Delta \quad m\quad (1)_{cb}}}} & \frac{\Delta \quad {m(1)}_{back\_ cb}}{{{\Delta \quad m\quad (2)_{cb}}}} \\\frac{\Delta \quad {m(1)}_{front\_ cb}}{{{\Delta \quad m\quad (1)_{cb}}}} & \frac{\Delta \quad {m(1)}_{front\_ cb}}{{{\Delta \quad m\quad (2)_{cb}}}}\end{bmatrix}^{- 1}}}} & (11)\end{matrix}$

[0058] The equation relationships shown in equation 9 can be rearrangedto solve for the counterbalance forces, Δm_(back) and Δm_(front),required to bring the system into balance. Utilizing the A matrix fromequation 11 for the case of four sensors, a relationship can beexpressed through equation 12 as follows: $\begin{matrix}{\begin{bmatrix}{\Delta \quad m_{back}} \\{\Delta \quad m_{front}}\end{bmatrix} = {A^{+} \cdot \begin{bmatrix}a_{back} \\a_{front} \\f_{back} \\f_{front}\end{bmatrix}}} & (12)\end{matrix}$

[0059] In a situation such as that described by equation 12 above, foursensor values (i.e., two accelerations and two forces) are generallyknown from measurements. Two counterbalance forces are unknown. Thisresults in a situation where there are more equations than unknowns aseach sensor provides an equation. Conversely, there are only two unknowncounterbalance forces for the front and back planes of the drum. Thiscondition describes an over-determined system and a technique generallyrequired to solve for more equations than unknowns in an optimal manner.

[0060] A technique for solving equations of this type in a balancingscheme should find a solution that minimizes all of the sensor readingsand also minimizes the amount of counterbalance media required tobalance the rotating system or rotating device. In other words, theforce sensors and the accelerometers should all be driven as close tozero as possible by the selected counterbalances and the total amount ofcounterbalance media (i.e., fluid or mass) applied be minimized.

[0061] Those skilled in the art can appreciate that a mathematicaltechnique, which may solve this problem involves computation of thepseudo inverse of the A matrix (A⁺) utilizing a singular valuedecomposition (SVD) technique. This solution method finds the optimalsolution to the inconsistent system represented simply by equation 9.The SVD is one of several techniques that can support the pseudo-inversecalculation for control. It can provide optimal control for both inputsand outputs of the modeled system. Other variations of the componentsthat make up the SVD may be used alone but would not provide both inputand output optimization. This procedure is fully described in U.S. Pat.No. 5,561,993, which is incorporated by reference herein. The SVDtechnique is well known to those skilled in the art and is described insignificant detail in various reference linear algebra textbooks.

[0062] After generating the solution to equation 12, it may be necessaryto formulate a practical approach to applying the counterbalance mass tothe rotating member. Further, after the control action is applied it maybe necessary to evaluate the member to verify that the control actionhad the desired balancing affect. In an ideal system, the force appliedto the rotating portion of the member is linearly related to the forceand motion that the sensors measure. In this ideal system the placementof the optimal counterbalances determined by the solving the system inthe manner described herein should drive all of the sensors to zero andachieve perfect balance of the rotating member.

[0063] For various reasons, however it is not expected that an idealsystem exists and certain system-balance, operational safety, andphysical constraints should be considered. An approach to applyingcounterbalance and verifying the control action effect is fullydescribed in U.S. Pat. No. 5,561,993, which is incorporated herein byreference. Those skilled in the art can appreciate that the approachesto applying counterbalance and verifying the control action affect,which were disclosed in U.S. Pat. No. 5,561,993, do not limit the scopeof the present invention. The features, techniques, methods and systemsdisclosed in U.S. Pat. No. 5,561,993 are described herein forillustrative and background purposes only.

[0064] In applying counterbalance and verifying the control action, in apreferred embodiment of the present invention, “system-balance”,operational safety, and physical constraints can be evaluated based onthe concept of sensor measurement thresholds and metrics. In regard tothe thresholds, the extremes are the balance threshold and the maximumthreshold. The balance threshold defines the sensor level below whichthe rotating member is defined as being in a balanced state. The maximumthreshold defines the sensor level above which the rotating membershould not be for any extended length of time. Intermediate thresholdsestablish levels at which balance control versus speed control decisionsget made. The system-balance and operational safety constraints maydirect the top-level control sequence.

[0065] Physical limits and safety evaluation impact control actionsoperating points between the balance and the maximum threshold levels.The control actuator applies a physical limit on the amount of inputthat can be applied to the system at any one time (smallest andlargest), as does the physical design of the rotating member in terms ofaccommodating the counterbalance mass. These physical limits areevaluated in terms of their ability to affect sensor responses by anamount less than the balance threshold with sufficient room to operate(i.e., allow multiple control actions) within the balance to maximumthreshold range. Given sufficient room to operate, the size andcorrectness of a recommended counterbalance action may be a safetyconcern. A large recommended counterbalance action or an incorrectlyplaced counterbalance may increase rather than decrease the degree ofout-of-balance; as such, it may not be prudent to apply the entirecounterbalance to the member in one control action. Thus, a set oflimits may be used to safely apply the recommended counterbalance actionto the rotatable member. Conversely, system-balance constraints comeinto play when control actions, counterbalance or test are used tocreate or update the control model as described above; these actionsshould be large enough to provide a good approximation of slope, asillustrated in FIG. 1.

[0066] System-balance constraints further influence counterbalancecontrol actions in terms of maintaining the desired control trajectory.In the configuration being used for illustration of the concepts herein,counterbalances are applied to the spinner by simultaneously injecting apredetermined mass of water across a predetermined range of rotationangles in both the front and back planes of the spinning member at thecurrent rotational speed. The result of the injection can be resolvedmathematically to determine the net counterbalance force applied to thesystem or to resolve the net force into its front and back planecomponents.

[0067] In order to apply the desired force, the water is often injectedover a number of revolutions of the apparatus. This progressive natureof the counterbalance action may make it necessary to maintain theproper vector direction of the force throughout the control action inorder to evaluate the system after each successive step along thecounterbalance force vector and make decisions more quickly duringproblem periods. To maintain this direction, it may be useful toestablish a ratio between the magnitudes of the front and back planeelements in the force vector on the left side of equation 12. Thisfront-to-back ratio is defined by equation 13. $\begin{matrix}{{{front\_ to}{\_ back}{\_ ratio}} = \frac{\Delta \quad m_{front\_ cb}}{\Delta \quad m_{back\_ cb}}} & (13)\end{matrix}$

[0068] Lastly, system-balance constraints are associated with thenon-linearity and time-varying nature of the system and its imbalanceacross operating speeds. Meeting the necessary constraints outlinedabove, the response to the counterbalance actions is measured and may beused to update the control model to account for the system non-linearityand time-varying dynamics. Measurements of the forces and motions atvarious locations within the rotatable apparatus are made before andafter each control action and may be used to update the control modeldescribed by equations 9 through 12. That updated model along withfurther sensor measurements may be utilized to determine a prediction ofthe next required correction counterbalance control action. If the priorcontrol action cannot be used to update the control model, test actionsare created. This process continues until balance condition is achieved(i.e., all sensor values below balance threshold) at full operatingspeed.

[0069] Systems and methods utilized to determine whether or not thecontrol model is performing well and if prior actions can be utilized toupdate the control model, as well as methods for determining qualitytest action in the event prior control actions cannot be used directly,are the subjects of the present invention. Given a recommendedcounterbalance control action, the previously described constraints areapplied to divide it into appropriately sized control sets, the sum ofthe sets defining the whole control action. After each control set, thebalance control system utilizes various conditions or metrics to assessthe affect that the action had on the system. As described earlier, thefirst condition is a comparison of the individual sensor measurementmagnitude to its respective balance thresholds. Another set of relatedsystem conditions or metrics is based on a global or aggregate sensormeasure of the system and the distribution of the sensor measurements.The information that is of interest is the amount that this globalmeasure changes between incremental steps along the recommended controlaction as well as the running sum of the changes over the entirerecommended control action. The distribution metric indicates whetherone sensor measure strongly influences the global metric or that severalsensor measures have contributed. Together, the global and distributionmetrics are used to assess control model performance and determine ifsufficient information is available to update the control model. Therate at which the system is changing is also evaluated based on theglobal sensor measure and is used to anticipate control modelperformance.

[0070] The global measure that may be used is a cost function of theform:

J=[Σw₁ |f(m₁)|^(n)]^(1/n)  (14)

[0071] In equation 14, m may be a complex vector representing the inputforces applied to the rotating member and experienced by the system. Inthe preferred embodiment a force couple at the front and back of therotating member can be used to uniquely describe these forces. As such,counterbalance force changes may be applied at the front and back planesof the rotating member. The function f(m_(i)) represents the ithcomponent of a complex vector of sensor measurements at the conditioncorresponding to each m. Additionally, f(m_(i)) is defined as athreshold function where there is some minimum value below which thefunction evaluates to zero and above which the function assumes themagnitude of f(m_(i)); the minimum values may be determined based on thesensor resolution or the amount of sensor noise in the system. The w_(i)term may represent a weighting for the ith sensor. Such a weighting maybe determined in a number of ways and may generally be used to emphasizecertain sensors of interest. The variable n may be chosen to define theshape of the surfaces that the global measure defines in the sensorspace, a value of 2 corresponds to ellipses and a value of infinitycorresponds to squares. The shape of the surfaces defines therelationship among all the different types of sensors and theircorresponding vector directions.

[0072] This cost function as described above provides a global metric ofthe present sensor magnitude condition. By replacing f(m_(i)) inequation 14 with Δf(m_(i)) or ΣΔf(m_(i)), it can likewise be used toprovide a global metric of the change in sensor magnitude over oneincrement of the control action or the change in sensor magnitude overthe running sum of the incremental control actions, respectively.

[0073] The distribution metric is intended to show how the affect of thecontrol action distributes across the sensor measurements. In this way,a better decision can be made regarding use of the global metric.Implementation of the distribution metric can be a simple threshold andtracking of the sensor measurements. The change in a sensor measurementshould be at least a designated multiple of the sensor measurement errorand at least two sensor measurements would have exceeded this limit inorder for a global metric computation to be performed. Alternatively,standard statistical distribution methods may be used to accomplish thedesired metric.

[0074] The global metric, qualified by the distribution metric, can becompared before and after a control action to determine if in generalthe balance condition improved. If the present magnitude of the globalmetric is larger than the previous value, then the system can bedetermined to be getting worse, indicating a bad recommended controltrajectory. In the system described in U.S. Pat. No. 5,561,993 thesystem improvement was evaluated based on an individual sensor level andthe system could be classified as getting worse when only one sensorincreased in value. If this sensor was below its balance threshold andall the other sensors were improving, the supervisory control may havestopped a control action that would have eventually balanced the system.This global and distribution metric approach allows one to evaluate theentire system so that an individual sensor does not bias all of the massplacement supervisory control decisions.

[0075] Another method that can be used to evaluate the performance ofthe control model between control actions involves the rate at whichglobal measure is changing. As was previously described, a controlaction can be too large and go beyond balancing the system to creatingan “out of balance” 180 degrees across from the previous “out ofbalance”. If operating in a region where the rotatable system responsebecomes particularly non-linear, as depicted in FIG. 1, a balancedcondition may be rapidly approached with the first few control sets. Anadditional example is that while moving into and out of a resonancecondition, the rate of change of the global function can vary sharply,indicating that the dynamics of the system are quickly changing and thevalidity of the control model is decaying. In any case, if the linearcontrol model poorly represents the actual system performance curve,each control set will move the system further from what is expected andthe rate of change in the global metric may be a leading indicator ofthis. An increased or decreased rate of change can be used to make adecision to stop injecting mass, before continued injection of masscreates a worse condition.

[0076] With these methods for determining control model performance andusability of the latest system response to control actions to update thecontrol model, it is conceivable that at some point, for variousreasons, the control model performance will be poor or inadequate andthe previous control responses inadequate for updating the controlmodel. In these circumstances, test actions are required; rather thanapplying random test actions, test actions that may benefit balancecontrol are desirable and can be computed (i.e., smart test actions).There are several defining cases for producing test actions. The firstcase involves the situation in which no prior control model exists orconsecutive control responses have not provided enough information toupdate the control model. In this first case, two predefined andsufficiently different test actions are utilized.

[0077] The second case involves the situation in which a prior controlmodel exists, but the system has experienced a substantial change inoperating conditions, (e.g., a change in rotational speed). The systemin question is not an ideal linear system. Thus, when a model is createdat one speed and the speed is then increased, the model may no longer bevalid. Yet, it remains the “best guess” at a course for control action.Thus, at each new speed, the first or initial test actions at the newspeed can be calculated based on the last model formed at the previousspeed, along with the current sensor measurements. The recommendedcontrol action can be broken down into two separate and sufficientlydifferent test actions: “smart test actions.” Given a desiredcounterbalance vector, v, one may wish to find vectors v₁ and v₂ suchthat v can be broken into two sufficiently different test actions, suchas shown in equation 15:

desired_counterbalance=

$\begin{matrix}{{{\left\lbrack {{\overset{\rightharpoonup}{v}}_{1}{\overset{\rightharpoonup}{v}}_{2}} \right\rbrack \begin{bmatrix}1 \\1\end{bmatrix}} = \left\lbrack \overset{\rightharpoonup}{v} \right\rbrack}{{{i.e.{\overset{\rightharpoonup}{v}}_{1}} + {\overset{\rightharpoonup}{v}}_{2}} = \overset{\rightharpoonup}{v}}{{\overset{\rightharpoonup}{v}}_{1} = {\frac{\overset{\rightharpoonup}{v}}{2} + \overset{\rightharpoonup}{w}}}{{\overset{\rightharpoonup}{v}}_{2} = {\frac{\overset{\rightharpoonup}{v}}{2} - \overset{\rightharpoonup}{w}}}} & (15)\end{matrix}$

[0078] To determine vector w and ensure sufficient difference betweenvectors v₁ and v₂, the desired condition is that the vectors w and v, aswell as vectors v₁ and v₂, are orthogonal, as expressed in equation 16.

^(T)

=0 or

*

=0

and

₁*

₂=0  (16)

[0079] The condition on vectors v₁ and v₂ can be expanded to determinethe requirement on the magnitude of w, shown in equation 17.$\begin{matrix}{{{\left( {\frac{\overset{\rightharpoonup}{v}}{2} + \overset{\rightharpoonup}{w}} \right)^{*}\left( {\frac{\overset{\rightharpoonup}{v}}{2} - \overset{\rightharpoonup}{w}} \right)} = {{\frac{{\overset{\rightharpoonup}{v}}^{2}}{0} - {\overset{\rightharpoonup}{w}}^{2}} = 0}}{{\overset{\rightharpoonup}{w}} = \frac{\overset{\rightharpoonup}{v}}{2}}} & (17)\end{matrix}$

[0080] Performing a singular value decomposition of vector v yields anorthogonal or unitary matrix U, whose columns are orthogonal unitvectors U₁ and U₂, as shown in equation 18. Vector v is a scalarmultiple of vector U₁, thus vector U₂ is orthogonal to vector v and,using the result from equation 17, can be used to construct vector w andthe two desired test action vectors, v₁ and v₂, as shown in equation 18.$\begin{matrix}{{{\left( {\frac{\overset{\rightharpoonup}{v}}{2} + \overset{\rightharpoonup}{w}} \right)^{*}\left( {\frac{\overset{\rightharpoonup}{v}}{2} - \overset{\rightharpoonup}{w}} \right)} = {{\left\lbrack \frac{\overset{\rightharpoonup}{v}}{0} \right\rbrack \left\lbrack x_{1} \right\rbrack} = {{{\left\lbrack {{\overset{\rightharpoonup}{U}}_{1}{\overset{\rightharpoonup}{U}}_{2}} \right\rbrack \left\lbrack \frac{\overset{\rightharpoonup}{v}}{0} \right\rbrack}\left\lbrack x_{1} \right\rbrack} = {{\overset{\rightharpoonup}{v}} \cdot x_{1} \cdot \left\lbrack {\overset{\rightharpoonup}{U}}_{1} \right\rbrack}}}}{Therefore}{\overset{\rightharpoonup}{w} = {\frac{\overset{\rightharpoonup}{v}}{2}{\overset{\rightharpoonup}{U}}_{2}}}{{And}\quad {the}\quad {test}\quad {action}\quad {vectors}\quad {become}}\text{}{{\overset{\rightharpoonup}{v}}_{1} = {\frac{\overset{\rightharpoonup}{v}}{2} + {\frac{\overset{\rightharpoonup}{v}}{2}{\overset{\rightharpoonup}{U}}_{2}}}}{{\overset{\rightharpoonup}{v}}_{2} = {\frac{\overset{\rightharpoonup}{v}}{2} - {\frac{\overset{\rightharpoonup}{v}}{2}{\overset{\rightharpoonup}{U}}_{2}}}}} & (18)\end{matrix}$

[0081] Using these sufficiently different test actions, derived from adesired control action is an improvement over the procedure described inU.S. Pat. No. 5,561,993, where arbitrary test actions were applied ateach new speed.

[0082] The third case is when a prior control model exists or a firsttest action has been performed, and the control model needs a partialupdate, i.e., only one column of the A matrix needs updating; but thesystem response to the prior control action was not adequate to updatethe control model or the response to the first test action was notsufficiently different from the desired second test action. Thus, asingle test action is needed that is sufficiently different from thelast control or test action used to update the control model. Again,computing an appropriate test action involves the determination of avector U₂ that is sufficiently different from the last control or testaction that was used to update the model, referred to as Δ

₁. There are many mathematical techniques that can be utilized todetermine a vector that is sufficiently different from Δ

₁, in the preferred embodiment, and as with the prior case, the methodselected involves the use of the singular value decomposition. Thoseskilled in the art will recognize that this choice of method does not inany way limit the invention. For the same reasons described regardingequation 18, the solution to the equation 19 provides the vector

₂ that is sufficiently different from Δ

₁. $\begin{matrix}{{{{\left\lbrack {{\overset{\rightharpoonup}{U}}_{1}{\overset{\rightharpoonup}{U}}_{2}} \right\rbrack \begin{bmatrix}\sigma_{1} \\0\end{bmatrix}}{\overset{\rightharpoonup}{x}}_{1}^{*}} = {{svd}\left( {\Delta \quad {\overset{\rightharpoonup}{m}}_{1}} \right)}}{{{where}:\text{}{\begin{bmatrix}\sigma_{1} \\0\end{bmatrix}{represents}\quad {the}\quad {singular}\quad {value}\quad {of}\quad \Delta \quad {\overset{\rightharpoonup}{m}}_{1}}},{\sigma_{1} = {{\Delta \quad {\overset{\rightharpoonup}{m}}_{1}}}}}{{\overset{\rightharpoonup}{x}}_{1}^{*}\quad {is}\quad 1 \times 1}{{{and}\quad \frac{\Delta {\overset{\rightharpoonup}{m}}_{1}}{{\Delta \quad {\overset{\rightharpoonup}{m}}_{1}}}} = {{\overset{\rightharpoonup}{U}}_{1} \cdot {\overset{\rightharpoonup}{x}}_{1}}}} & (19)\end{matrix}$

[0083] The sufficiently different test action described by vector U₁ isan action that is primarily meant to update the control model and has inno way been optimized to balance the system. Thus, it may be scaled tothe minimum test size necessary to perturb the system.

[0084] With the general approach and constraints to placing massdescribed, and the new performance metrics defined, along with methodsfor computing test actions, consider the supervisory method and systemfor improved control model updates. FIG. 9 illustrates a statetransition-type diagram 360 illustrating operational steps forimplementing a balance control loop that includes deliberate updates tothe control model, exploiting the performance metrics and test actioncomputations described herein. In accordance with a preferred embodimentof the present invention, the operations depicted in FIG. 9 describe asequence of operations and conditions regarding the types of decisionsthat are generally made in balancing a rotating apparatus at each speedincrement. A balance control loop supervisor passes information to aspeed change supervisor so that a decision to increase or decrease speedcan be carried out until a maximum speed is achieved.

[0085] The process begins, as illustrated at block 362. Initializationoccurs, as indicated at block 364. If it is the first time within thebalance control loop, as described at transition point 370, the “computetest injections” operation indicated at block 376 may occur immediatelyfollowing initialization. Block 376 is fully described and representsthe state transition type diagram illustrated in FIG. 10.

[0086]FIG. 10 depicts a state transition type diagram 440 illustratingoperational steps for computing test actions, in accordance withpreferred embodiments of the present invention. The process can beinitiated, as illustrated at block 442. In the case where this block wasentered under the condition described by transition point 374 of FIG. 9,two sufficiently different vectors or test actions may be created, asindicated at block 452. Two sufficiently different vectors (i.e., testactions) may be created if a balanced state has not been achieved andupdates cannot be made to the control model based on prior controlactions, as illustrated at transition points 446 and 448. These two testvectors can be any two actions that are predetermined to be sufficientlydifferent.

[0087] In the case where a new speed may be entered, as illustrated attransition point 368 of FIG. 9, initialization is followed by computingthe desired control action, as indicated at block 366, and test actionscan then be derived from the desired control action, as illustrated atblock 376. In this situation, the operation to compute test injectionsis entered because the system has just entered a new speed as describedby the transition point 464 of FIG. 10. At the previous speed, thealgorithm created a model to predict the best course of action for thenext counterbalance. As discussed earlier, a speed change may cause thecontrol model to no longer be valid, yet, it provides a good estimationat a course of control action. Thus, at each new speed a first controlaction is determined from the last good model, then scaled back due tothe fact that it may not be an optimal solution, and then separated intotwo sufficiently different test actions, as illustrated at block 462 ofFIG. 10 and discussed in equations 15 through 18. The test actions areintended to provide an adequate system response to update the controlmodel.

[0088] After one or more test actions are calculated, the initial testaction may then be placed on the spinner, as illustrated at block 378 ofFIG. 9. Specific operational steps that can be implemented to carry outthe operation described at block 378 of FIG. 9 are illustrated in FIG.8. Thus, as illustrated at block 302, the “Place Mass on Spinner”process is initiated. As indicated next at block 304, the sensor valuesare recorded for use as initial values, (sensor measurement prior to anyaction). These values are later used to determine the change in sensormeasurements due to the control action and to provide inputs to theglobal, distribution and rate metrics, described earlier, to assesssystem performance.

[0089] As depicted thereafter at block 306, a desired action isseparated into one or more control sets whose aggregate represents thefull control action. As illustrated next at block 308, one set is placedon the spinner. Then, as indicated at block 314, the sensors are checkedagain and compared to balance, maximum, and intermediate thresholds. If,as indicated at block 346, a maximum speed has been exceeded, and anupdate flag is equivalent to a NO value, the process simply terminates,as illustrated at block 334. Alternatively, the process may alsoterminate if, as illustrated at block 348, a balanced state has beenachieved, but an update flag is also equivalent to a NO value.

[0090] It may be useful at this time to describe the update flag. Theupdate flag is used to indicate whether or not a control (or test)action is suitable to update the control model. The major criterion hereis that the action is sufficiently different than the last action sothat the adjacent columns of the A matrix are independent with respectto the criterion of interest to the particular application. Anothercriterion that dictates whether or not an action is suitable to updatethe model is that the action is large enough to produce a suitableresponse in the system, i.e., a change in the sensors that is greaterthan the system noise. The last criterion places a lower limit on thenumber of sensors that have changed by more than the system noise. Thesecond and third criteria correspond to the distribution metric and theminimum change in the sensor measurements required for that measurementto be included in the global aggregate sensor measure. The majorcriterion defining the status of the update flag is analyzed in block416 of FIG. 9. This block corresponds to the logical operations depictedin the state transition type diagram of FIG. 11.

[0091]FIG. 11 illustrates a state-transition-type diagram 500illustrating operational steps that may be implemented to determine ifcontrol actions are sufficiently different from one another, inaccordance with preferred embodiments of the present invention. Thus, asdescribed at block 502, the process is initiated. Thereafter, asindicated at blocks 506 and 508, two possible operational paths may befollowed. If there have been two test actions computed and the firsttest action is complete, as indicated at transition point 505, then theoperation described at block 506 is processed, in which a desired secondtest action is compared to the actual first test action. In the casewhere the system has completed at least one recommended control actionand the rotatable system or apparatus requiring balancing did notbalance, but is in a condition that allows for a control model update,as described at transition point 503, then the desired control actioncan be compared to the last action utilized to update the control model,as indicated at block 508. Likewise, in situations where balancingcontinues at the same speed with a new A matrix in the control model asdepicted at transition point 507, then a desired control action can becompared to the last action utilized to update the control model, asindicated at block 508. These last two cases are described by blocks 392and 396, as well as transition point 402, of FIG. 9.

[0092] Following the operations described at both blocks 506 and 508 theupdate flag is set, as indicated at block 510. Here, if the actions areconsidered sufficiently different, the update flag is set to a “YES”state, as described at transition point 513. Conversely if the actionsare NOT considered sufficiently different, the flag is set to NO, andafter the operation at block 510 the update flag may be equivalent to a“NO” state, as illustrated at transition point 515. After the flag isset the function returns to the balance loop described in FIG. 9.

[0093] Continuing in the description of FIG. 8 in the cases whereneither of the conditions described by transition points 346 or 348occur, a delta sensor value can be calculated for a particular set, asdescribed in block 316. In the case where the set being applied is notthe first, as shown in transition point 320, the change over all of thesets that have made up the current action are calculated, as illustratedat block 318. Otherwise the total change is the same as the delta or setchange and the process moves to block 322. In block 322 the total sensorchange is evaluated using the distribution and global sensor criteriadescribed herein.

[0094] Based on the evaluation indicated in block 322, many differentconditions may arise, which conditions are described by transitionpoints 310, 312, 324, 326, 328, 330, 336, 340, 342, and 344. Forexample, the operation illustrated at block 308 may be processed suchthat an additional control set is placed on the spinner. This scenariomay occur when the test action requires another or a progressive set ofactions to accomplish the test, as illustrated at block 312, or if thesensors improve but do not achieve a balanced state, so additionalcontrol sets are applied, as indicated at block 310.

[0095] In all the cases defined by transition points 324 to 330, theaction is recorded and converted to a form that can be used to updatethe system model as indicated by block 332. Transition point 324 isreached when the rotating apparatus is in balance and the prior controlor test action is considered to be “good” for the model update. Recallthat the term “good” for a model update may mean that the change in theminimum number of sensors is greater than the system noise and theglobal change in sensors is considered to be sufficient. Transitionpoint 326 covers the case where the action was merely a test action andthis test action has met the “good” for update conditions. If the globalsensor criterion indicates the system became worse or one of theindividual sensor measurements exceeded its maximum threshold, but thesystem has still met the “good” for update criteria, the situations aredescribed by transition points 328 and 330, respectively.

[0096] For the other transition points that can occur as a result of theevaluation described at block 322, the control model cannot be updatedand the system immediately returns to the balance loop. In theconditions described by 336 and 340, the system gets worse and theaction is not suitable for updating the model. In the transition pointdescribed by 344 the sensor change is too small and no determinationscan be made. Finally in the case described by transition point 342 thesystem has reached a balanced state but the action was not suitable toupdate the model. For the cases described by transition points 340 to344, the update flag is set to NO. In the case described by transitionpoint 336, the update flag was already NO. In all cases this informationis then passed back to the balance loop that continues operation atblock 378 (in FIG. 9) armed with the new information from the place massfunction.

[0097] After the actions described by block 378 and FIG. 8 are carriedout, numerous additional conditions may arise. If the sensor measurementchange is too small, the sensor measurements are worse with aninsufficient change to update the control model, and the rotatableapparatus (i.e., rotating device or rotating system) did not achieve abalanced state, as respectively depicted at blocks 382, 380, and 374,then the operation illustrated at block 376 may be repeated. The logicaloperation illustrated at block 376 is described in greater detail viathe remaining logical operations illustrated in FIG. 10. In these cases,the previous counterbalance action cannot be used to update the controlmodel. Thus, one sufficiently different test action may be created, asindicated at block 454 of FIG. 10. If a control action is completed, abalanced state is not achieved, and the last action was inadequate toupdate the control model, transition point 456, or the most recentsensor measurement change due to control or test action is not large ordifferent enough, transition points 458 and 460, then a singlesufficiently different test action may be created, as illustrated atblock 454. The procedure discussed in relation to equation 19 may beperformed to determine an appropriate test action. This proceduredescribes the details of block 454.

[0098] Once a new test action has been created by one of the methods ofFIG. 10, the operation described at block 378 and in FIG. 8, in which atest action is taken on the rotating apparatus, is repeated. Many of theconditions that are indicated as transition points in FIG. 9 directlycorrespond to transition points from FIG. 8. The conditions oftransition point 406 and 408 for example correspond to 346 and 348respectively. Transition point 408 also corresponds to transition point342. In all of these cases the system cannot continue at the currentspeed so the system exits the balance control loop with the appropriateinformation as described at block 412 of FIG. 9. The control strategywill return to the speed control portion to decide whether a speedincrease or decrease is required.

[0099] All of the transition conditions from FIG. 8 that lead to block332 (i.e., transition points 324, 326, 328, and 330) result in an updateto the control model. These transition points correspond to 384, 388,390 and 386 of FIG. 9, respectively, and result in the action ofcomputing a new column of the A matrix in the control model, asindicated at block 392. The conditions associated with this action areas follows. First, as illustrated at block 384, the rotatable apparatusmay have achieved a balanced state and updates to the control model canbe made. Second, as described at block 386, a maximum threshold has beenexceeded, but updates to the control model may still be made. Third, asindicated at block 388, the sensor measurements may have improved,indicating a more balanced system, but may require a new control modelto achieve a balanced state. Fourth, as described at block 390, thesensor measurements may have become worse, but have changed sufficientlyto allow updates to the control model.

[0100] Following processing of the operation described at block 392, ifwe are in the middle of applying two test actions and have only finishedthe first one, as indicated in transition point 404, then a check can beperformed to determine if the resulting sensor measurement response tothe initial test action is sufficiently different from the desiredsecond test action, as illustrated at block 416. Block 416 isrepresented in more detail in FIG. 11 as has previously been describedherein. In the case where transition point 404 leads to block 416 inFIG. 9 the first test injection is complete, as indicated at transitionpoint 505 (FIG. 11), then the operation described at block 506 isprocessed, in which a desired second test action is compared to theactual first test action. This test may be generally referred to as a“difference check.”

[0101] As has previously been described herein, in order to achieve agood model of a given system in which the rotatable apparatus operates,test masses may be required that are sufficiently different (i.e.,orthogonal) from one another to excite the system in sufficientlydifferent directions. Alternatively, when there is no next test actionwaiting to be applied, a desired control action may be computedfollowing completion of the operation described at block 392. Thedesired action can be computed utilizing the calculated A matrix, asindicated at transition point 394. If, following processing of theoperation illustrated at block 396, a balanced state has been achievedand the control model can be updated, as illustrated at transition point398, or a maximum speed has been exceeded and the control model can beupdated, the system exits the balance loop with the appropriateinformation as described at block 412 and the control strategy willreturn to the speed control portion to decide whether a speed increaseor decrease is required.

[0102] If, following completion of the operation depicted at block 396in which a desired action is computed, balancing continues at the samespeed with a new A matrix model, as indicated at transition point 400.In addition, if a balanced state has not been achieved, but updates canbe made to the control model, as illustrated at transition point 402,then the operation illustrated at block 416 may occur immediatelyfollowing processing of the operation depicted at block 396. After acheck has been made to determine if particular control actions aresufficiently different from one another, the operation depicted at block378 may be repeated. Alternatively, if a first test has been achievedvia control or test actions, but the subsequent control or test actionsare not sufficiently different, then determination of a second test maybe desired, as indicated at block 372. In this case, the operationillustrated at block 376 may be repeated, in which test actions arecomputed.

[0103] Those skilled in the art can appreciate that this strategy can beimplemented on a batch of collected data if a serial implementation isutilized. The algorithms, however, may not require batch data oroff-line processing and can be implemented on a sample-by-sample basisor in real time with a processor and data collection approach that issufficiently fast. At least one revolution of data should generally beprocessed to determine the action parameters.

[0104] Those skilled in the art can further appreciate that theoperational steps depicted in FIGS. 8 to 11 may be implemented asprogram code or as a software module or series of related softwaremodules. Such modules may be integrated with hardware to performparticular operational functions. The term “module,” as known by thoseskilled in the computer programming arts, generally refers to acollection of routines, subroutines, and/or data structures, whichperform a particular task or implement certain abstract data types.Modules are generally composed of two features. The first feature can beimplemented as an interface, which compiles the constants, data types,variables, and routines. The second feature can be configured as aprivate algorithm that is accessible only by the module and whichincludes the source code that activates the routines in the module ormodules thereof. A software implementation of the present invention maythus involve the use of such modules and/or implementation of a programproduct based on the operational steps illustrated in FIGS. 8 to 11herein. Such a program product may additionally be configured assignal-bearing media, including recordable and/or transmission media.

[0105] The embodiments and examples set forth herein are presented tobest explain the present invention and its practical application and tothereby enable those skilled in the art to make and utilize theinvention. Those skilled in the art, however, will recognize that theforegoing description and examples have been presented for the purposeof illustration and example only. Other variations and modifications ofthe present invention will be apparent to those of skill in the art, andit is the intent of the appended claims that such variations andmodifications be covered. The description as set forth is not intendedto be exhaustive or to limit the scope of the invention. Manymodifications and variations are possible in light of the above teachingwithout departing from the spirit and scope of the following claims. Itis contemplated that the use of the present invention can involvecomponents having different characteristics. It is intended that thescope of the present invention be defined by the claims appended hereto,giving full cognizance to equivalents in all respects.

The embodiments of an invention in which an exclusive property or rightis claimed are defined as follows:
 1. A method for dynamically balancinga rotating system through strategic control model updates, wherein saidrotating system includes sensors and sensor measurements thereof whoseresponses to control actions are utilized to represent said rotatingsystem through a control model, wherein said control model and saidsensor measurements are determinative of future control actions, saidmethod comprising the steps of: anticipating a control model performanceutilizing metrics and evaluations of said sensor measurements and saidresponses thereof to determine if it is necessary to update said controlmodel; determining if said sensor measurements and said responsesthereof are adequate for use in updating said control model utilizingsaid metrics; computing at least one select control action that excitessaid rotating system to provide a sufficiently different sensormeasurement response adequate for use in updating said control model;and incorporating said metrics and evaluations and said at least oneselect control action into a balance control procedure to therebyimprove balance times and facilitate achievement of maximum spin speedswithin said rotating system.
 2. The method of claim 1 wherein the stepof computing a select control action, wherein said select control actionexcites said rotating system to provide a sufficiently different sensormeasurement response adequate for use in updating said control model,further comprises the step of: computing a select control action whencontrol model performance is poor and past control actions are notadequate for control model updates, wherein said select control actionexcites said rotating system to provide a sufficiently different sensormeasurement response that is adequate for use in updating said controlmodel.
 3. The method of claim 2 wherein the step of computing a selectcontrol action when control model performance is poor and past controlactions are not adequate for control model updates, wherein said selectcontrol action excites said rotating system to provide a sufficientlydifferent sensor measurement response that is adequate for use inupdating said control model, further comprises the step of: computing aselect control action when control model performance is poor and pastcontrol actions are not adequate for control model updates, wherein saidselect control action excites said rotating system to provide asufficiently different sensor measurement response adequate for use inupdating said control model, wherein said select control actionminimizes effects that do not contribute to balancing of said rotatingsystem
 4. The method of claim 1 further comprising the step of:calculating a plurality of select control actions when control modelperformance is questionable because operating conditions have changedsubstantially, such that said plurality of select control actions excitesaid rotating system to provide sufficiently different sensormeasurement responses adequate for updating said control model, whereinsaid plurality of select control actions minimize effects that do notcontribute to balancing of said rotating system
 5. The method of claim 1further comprising the step of: utilizing said metrics, sensormeasurements and sensor measurement responses thereof to determine whenand how to update said control model.
 6. The method of claim 1 furthercomprising the steps of: configuring said metrics to include a globalmetric, a distribution metric and a change rate metric, wherein saiddistribution metric includes sensor distribution data and said changerate metric includes sensor measurement response change rate data; andutilizing said metrics to evaluate a particular balance condition and todetermine whether sensor measurement responses are adequate for acontrol model update.
 7. The method of claim 6 wherein said globalmetric comprises an aggregate cost function that generates a singlemeasure representing a balance state and an additional single measurerepresentative of an overall response of said rotating system to pastcontrol actions.
 8. The method of claim 6 wherein said distributionmetric comprises a single measure representing a distribution ofindividual sensor contributions to said global metric.
 9. The method ofclaim 6 wherein said change rate metric comprises a change in anaggregate cost function, which generates a single measure thatanticipates control model performance.
 10. The method of claim 1 furthercomprising the step of: assessing said control model performance of saidrotating system utilizing at least one sensor integrated with saidrotating system to determine if sufficient information is available topermit an update of said control model.
 11. The method of claim 1wherein the step of computing a select control action that excites saidrotating system to provide a sufficiently different sensor measurementresponse adequate for use in updating said control model, furthercomprises the steps of: creating a control action vector sufficientlydifferent from previous control actions utilized in prior updates ofsaid control model; manipulating said control action vector to meetsystem-balance, operational-safety, and physical constraints; excitingsaid rotating system utilizing said control action vector; and updatingsaid control model utilizing resulting sensor measurement responses. 12.The method of claim 4 wherein the step of calculating a plurality ofselect control actions when a control model performance is questionablebecause operating conditions have changed substantially, such that saidplurality of select control actions excite said rotating system toprovide sufficiently different sensor measurement responses adequate forupdating said control model, wherein said plurality of select controlactions minimize negative balancing effects on said rotating system,further comprises the steps of: utilizing a control model from aprevious operating point and current sensor measurement responses toobtain a recommended control action for a subsequent control action;dividing said recommended control action into at least two sufficientlydifferent control action vectors whose cumulative effect excites saidrotating system sufficiently to update said control model; manipulatingsaid control action vector to meet system-balance, operational-safety,and physical constraints; and exciting said rotating system utilizingsaid control action vectors; and updating said control model utilizingresulting sensor measurement responses.
 13. The method of claim 1wherein the step of incorporating said evaluation and said selectcontrol action into a balance control procedure to thereby improvebalance times and facilitate achievement of maximum spin speeds withinsaid rotating system, further comprises the step of: creating an initialcontrol model utilizing a plurality of select control actions togenerate predictions of future control actions; applying said generatedpredictions in a predetermined manner to satisfy constraints of saidrotating system; evaluating a balance condition of said rotating systemutilizing a response of said system applied to said generatedpredictions; updating said control model when an improved control modelis required for convergence to obtain a balance condition at a set speedof rotation; formulating a new control model when changes in operationalconditions occur; and continuing said balance control procedure until amaximum rotational speed is obtained.
 14. The method of claim 13 whereinsaid operational conditions comprise a change of speed of said rotatingsystem.
 15. The method of claim 13 wherein said operational conditionscomprise a load change within said rotating system.
 16. A method fordynamically balancing a rotating system through strategic control modelupdates, wherein said rotating system includes sensors and sensormeasurements thereof whose responses to control actions are utilized torepresent said rotating system through a control model, wherein saidcontrol model and said sensor measurements are determinative of futurecontrol actions, said method comprising the steps of: anticipating acontrol model's performance utilizing metrics obtained by an evaluationof said sensor measurements and said responses thereof to determine ifit is necessary to update said control model; determining if said sensormeasurements and said responses thereof are adequate for use in updatingsaid control model utilizing said metrics; computing a select controlaction that excites said rotating system to provide a sufficientlydifferent sensor measurement response adequate for use in updating saidcontrol model; calculating a plurality of select control actions whencontrol model performance is questionable because operating conditionshave changed substantially, such that said plurality of select controlactions excite said rotating system to provide sufficiently differentsensor measurement responses adequate for updating said control model,wherein said plurality of select control actions minimize negativebalancing effects that could possibly add to greater system unbalance insaid rotating system; and incorporating said evaluation, said selectcontrol action and said plurality of select control actions into abalance control procedure to thereby improve balance times andfacilitate achievement of maximum spin speeds within said rotatingsystem.
 17. A method for dynamically balancing a rotating system throughstrategic control model updates, wherein said rotating system includessensors and sensor measurements thereof whose responses to controlactions are utilized to represent said rotating system through a controlmodel, wherein said control model and said sensor measurements aredeterminative of future control actions, said method comprising thesteps of: anticipating a control model's performance utilizing metricsand evaluations of said sensor measurements and said responses thereofto determine if it is necessary to update said control model;determining if said sensor measurements and said responses thereof areadequate for use in updating said control model utilizing said metrics;computing at least one select control action that excites said rotatingsystem to provide a sufficiently different sensor measurement responseadequate for use in updating said control model; configuring saidmetrics to include a global metric, a distribution metric and a changerate metric, wherein said distribution metric includes distributionsensor data and said change rate metric includes sensor measurementresponse change rate data; utilizing said metrics to evaluate aparticular balance condition and whether sensor measurement responsesare adequate for a control model update; and incorporating said metricsand evaluations and said at least one select control action into abalance control procedure to thereby improve balance times andfacilitate achievement of maximum spin speeds within said rotatingsystem.
 18. A system for dynamically balancing a rotating device throughstrategic control model updates, wherein said rotating device includessensors and sensor measurements thereof whose responses to controlactions are utilized to represent said rotating device through a controlmodel, wherein said control model and said sensor measurements aredeterminative of future control actions, said system comprising: modulefor anticipating a control model performance utilizing metrics andevaluations of said sensor measurements and said responses thereof todetermine if it is necessary to update said control model; module fordetermining if said sensor measurements and said responses thereof areadequate for use in updating said control model utilizing said metrics;module for computing at least one select control action that excitessaid rotating device to provide a sufficiently different sensormeasurement response adequate for use in updating said control model;and module for incorporating said metrics and evaluations and said atleast one select control action into a balance control procedure tothereby improve balance times and facilitate achievement of maximum spinspeeds within said rotating device.
 19. The system of claim 18 whereinsaid module for computing a select control action, wherein said selectcontrol action excites said rotating device to provide a sufficientlydifferent sensor measurement response adequate for use in updating saidcontrol model, further comprises: module for computing a select controlaction when control model performance is poor and past control actionsare not adequate for control model updates, wherein said select controlaction excites said rotating device to provide a sufficiently differentsensor measurement response that is adequate for use in updating saidcontrol model.
 20. The system of claim 19 wherein said module forcomputing a select control action when control model performance is poorand past control actions are not adequate for control model updates,wherein said select control action excites said rotating device toprovide a sufficiently different sensor measurement response that isadequate for use in updating said control model, further comprises:module for computing a select control action when control modelperformance is poor and past control actions are not adequate forcontrol model updates, wherein said select control action excites saidrotating device to provide a sufficiently different sensor measurementresponse adequate for use in updating said control model, wherein saidselect control action minimizes effects that do not contribute tobalancing of said rotating device
 21. The system of claim 18 furthercomprising: module for calculating a plurality of select control actionswhen control model performance is questionable because operatingconditions have changed substantially, such that said plurality ofselect control actions excite said rotating device to providesufficiently different sensor measurement responses adequate forupdating said control model, wherein said plurality of select controlactions minimize effects that do not contribute to balancing of saidrotating device
 22. The system of claim 18 wherein said metrics, sensormeasurements and sensor measurement responses thereof are utilized todetermine when and how to update said control model.
 23. The system ofclaim 18 wherein: said metrics are configured to include a globalmetric, a distribution metric and a change rate metric, wherein saiddistribution metric includes sensor distribution data and said changerate metric includes sensor measurement response change rate data; andsaid metrics are utilized to evaluate a particular balance condition andto determine whether sensor measurement responses are adequate for acontrol model update.
 24. The system of claim 23 wherein said globalmetric comprises an aggregate cost function that generates a singlemeasure representing a balance state and an additional single measurerepresentative of an overall response of said rotating device to pastcontrol actions.
 25. The system of claim 23 wherein said distributionmetric comprises a single measure representing a distribution ofindividual sensor contributions to said global metric.
 26. The system ofclaim 23 wherein said change rate metric comprises a change in anaggregate cost function, which generates a single measure thatanticipates control model performance.
 27. The system of claim 18further comprising: module for assessing said control model performanceof said rotating device utilizing at least one sensor integrated withsaid rotating device to determine if sufficient information is availableto permit an update of said control model.
 28. The system of claim 18wherein said module for computing a select control action that excitessaid rotating device to provide a sufficiently different sensormeasurement response adequate for use in updating said control model,further comprises: a control action vector sufficiently different fromprevious control actions utilized in prior updates of said controlmodel; wherein said control action vector is manipulated to meetsystem-balance, operational-safety, and physical constraints; whereinsaid rotating device is excited utilizing said control action vector;and wherein said control model is updated utilizing resulting sensormeasurement responses.
 29. The system of claim 21 wherein said modulefor calculating a plurality of select control actions in which a controlmodel performance is questionable because operating conditions havechanged substantially, such that said plurality of select controlactions excite said rotating device to provide sufficiently differentsensor measurement responses adequate for updating said control model,wherein said plurality of select control actions minimize negativebalancing effects on said rotating device, further comprises: a controlmodel utilized from a previous operating point and current sensormeasurement responses to obtain a recommended control action for asubsequent control action; wherein said recommended control action isdivided into at least two sufficiently different control action vectorswhose cumulative effect excites said rotating device sufficiently toupdate said control model; wherein said control action vector ismanipulated to meet system-balance, operational-safety, and physicalconstraints; wherein said rotating device is excited utilizing saidcontrol action vectors; and wherein said control model is updatedutilizing resulting sensor measurement responses.
 30. The system ofclaim 18 wherein said module for incorporating said evaluation and saidselect control action into a balance control procedure to therebyimprove balance times and facilitate achievement of maximum spin speedswithin said rotating device, further comprises: an initial control modelcreated utilizing a plurality of select control actions to generatepredictions of future control actions; said generated predictionsapplied in a predetermined manner to satisfy constraints of saidrotating device; a balance condition of said rotating device evaluatedutilizing a response of said system applied to said predictions; saidcontrol model updated when an improved control model is required forconvergence to obtain a balance condition at a set speed of rotation; anew control model formulated when changes in operational conditionsoccur; and said balance control procedure continued until a maximumrotational speed is obtained.
 31. The system of claim 30 wherein saidoperational conditions comprise a change of speed of said rotatingdevice.
 32. The system of claim 30 wherein said operational conditionscomprise a load change within said rotating device.
 33. A system fordynamically balancing a rotating device through strategic control modelupdates, wherein said rotating device includes sensors and sensormeasurements thereof whose responses to control actions are utilized torepresent said rotating device through a control model, wherein saidcontrol model and said sensor measurements are determinative of futurecontrol actions, said system comprising: module for anticipating acontrol model's performance utilizing metrics obtained by an evaluationof said sensor measurements and said responses thereof to determine ifit is necessary to update said control model; module for determining ifsaid sensor measurements and said responses thereof are adequate for usein updating said control model utilizing said metrics; module forcomputing a select control action that excites said rotating device toprovide a sufficiently different sensor measurement response adequatefor use in updating said control model; module for calculating aplurality of select control actions when control model performance isquestionable because operating conditions have changed substantially,such that said plurality of select control actions excite said rotatingdevice to provide sufficiently different sensor measurement responsesadequate for updating said control model, wherein said plurality ofselect control actions minimize negative balancing effects that couldpossibly add to greater system unbalance in said rotating device; andmodule for incorporating said evaluation, said select control action andsaid plurality of select control actions into a balance controlprocedure to thereby improve balance times and facilitate achievement ofmaximum spin speeds within said rotating device.
 34. A system fordynamically balancing a rotating device through strategic control modelupdates, wherein said rotating device includes sensors and sensormeasurements thereof whose responses to control actions are utilized torepresent said rotating device through a control model, wherein saidcontrol model and said sensor measurements are determinative of futurecontrol actions, said system comprising: module for anticipating acontrol model performance utilizing metrics and evaluations of saidsensor measurements and said responses thereof to determine if it isnecessary to update said control model; module for determining if saidsensor measurements and said responses thereof are adequate for use inupdating said control model utilizing said metrics; module for computingat least one select control action that excites said rotating device toprovide a sufficiently different sensor measurement response adequatefor use in updating said control model; module for configuring saidmetrics to include a global metric, a distribution metric and a changerate metric, wherein said distribution metric includes distributionsensor data and said change rate metric includes sensor measurementresponse change rate data; module for utilizing said metrics to evaluatea particular balance condition and whether sensor measurement responsesare adequate for a control model update; and module for incorporatingsaid metrics and evaluations and said at least one select control actioninto a balance control procedure to thereby improve balance times andfacilitate achievement of maximum spin speeds within said rotatingdevice.